1. Chapter 2

2. Energy - PE = mgh - the faster something moves the more KE
Energy - ability or capacity to do work on some form of matter
Potential energy (PE) - an objects internal energy or an objects potential to do work
- PE = mgh
- mass * gravity * height (above the ground)
Example - a volume of air aloft has more potential energy than that same volume of air just above the surface
Kinetic Energy (KE) – “Energy of motion” [ KE = 1/2mv2 ]
- (1/2) mass * velocity2
- the faster something moves the more KE
- EX. Strong wind vs. Light Breeze
- Volume of Water vs Volume of Air

3. Energy
Energy takes on many forms and can change from one form to another
Total amount of energy in the universe remains constant
- the energy lost during one process must be equal to the energy gained during another (law of conservation of energy)
The temperature of air is a measure of its average KE
measure of average speed of atoms and molecules
Higher temps = faster speeds = lower density

4. Temperature Scales
Kelvin Scale – Named after Lord Kelvin (1824 – 1907)
Begins at Absolute Zero (-273 Celsius)
Celsius Scale – Named after Anders Celsius (mid 1700’s)
Also known as Centigrade
0 was assigned the temperature that pure water freezes at sea level, 100 assigned to the temperature it boiled at sea level
Fahrenheit Scale – Named after Daniel Fahrenheit (1700’s)
32 assigned to number water freezes at, 212 the number it boils at and 0 assigned to lowest temperature obtained by mixing salt, water and ice
Rankine Scale – Named after William John Macquorn Rankine
Also begins at absolute zero (-460 Fahrenheit)

5. Heat
Heat - energy in the process of being transferred from one object to another because of the temperature difference between them
How is heat transferred in the atmosphere?
-conduction
-convection
-radiation

6. Conduction
Conduction is the transfer of heat from molecule to molecule within a substance

7. Convection
Convection is the transfer of heat by the mass movement of a fluid (water or air)

8. Radiation
Radiation is the energy transferred in the form of waves that is released when it hits an object

9. Specific Heat
Heat capacity - ratio of the amount of heat energy absorbed by the substance to its corresponding temperature rise
Specific heat - heat capacity of a substance per unit mass
Example:
1g of pure water takes 1 calorie to raise its temp by 1°C making it’s specific heat equal to 1
But…
1g of soil takes 1/5th of the heat to raise its temperature 1°C making its specific heat equal 0.2
Units of Specific heat = Cal/(gram * °C) or Cal gram-1 °C-1

10. Latent Heat
Latent Heat - heat energy required to change water from one state to another

11. Latent Heat
Latent heat released from the billions of vapor droplets during condensation and cloud formation fuels storm energy needs, warms the air, and encourages taller cloud growth.

12. Radiation Radiation E = T4 - Stefan-Boltzman Law
All things emit radiation
The wavelength of the emitted radiation generally depends on the objects temperature
The higher the temperature the greater the rate that energy is emitted
E = T4
- Stefan-Boltzman Law
E = Max rate of radiation emitted by each square meter of surface area of an object
= Stefan-Boltzman constant = 5.67 X 10-8 W m-2 K- 4
T = Temperature (K)

13. ** Check Appendix A in the book for more conversions
Converting Units
1 Joule = cal Energy
1 Watt = 1 Joule sec Power
1 millibar (mb) = ( in. Hg) = 100 pascals (Pa) Pressure
1 newton (N) = 1 kg m s Force
1 in = 2.54 cm
1 knot = 1 nautical mile per hour = 1.15 statute mile per hour
1 liter (l) = 1000 cm3
** Check Appendix A in the book for more conversions

14. Time Conversion
GMT / UTC / Z - Zulu time Conversion
MDT - Mountain Daylight Savings Time
Subtract 7-h [Midnight (00Z) = 5pm MDT]
MST - Mountain Standard Time
Subtract 6-h [Midnight (00Z) = 6pm MST]

15. Radiation
At what wavelengths () do the Sun and the Earth radiate most of their energy?
max = constant / T Wein’s Law
max = wavelength at which maximum radiation emission occurs (μm)
Constant = 2897 μm K
T = surface temperature

16. Sun’s Electromagnetic Spectrum

17. Radiation Maximums

18. Absorption, Emission, and Equilibrium
While all objects radiate energy, they absorb it as well
If an object radiated more energy than it absorbs, it gets colder and Vice Versa
Ex. On a sunny day, Earth’s surface warms by absorbing more energy than it radiates, but at night the earth cools by doing the opposite
The rate at which an object radiates or absorbs energy depends strongly on surface characteristics
- color, texture, and moisture
Example
A dark colored object in direct sunlight is a good absorber of visible radiation
Converts energy from the sun into internal energy
At night, it will cool very quickly by emitting IR radiation

19. Absorption, Emission, and Equilibrium
Any object that is a perfect absorber (absorbs all radiation that strikes it) and a perfect emitter (emits all radiation at a given temp) is called a blackbody (An object does not have to be colored black to be a blackbody)
The Earth’s surface and the sun absorb and radiate with nearly 100% efficiency
Earth and Sun behave as blackbodies
This why we can use the Stefan-Boltzman and Wein’s Laws
Radiative equilibrium temperature – rate of absorption = rate of emission
Is Earth’s atmosphere a black body?
Objects that selectively absorb and emit radiation are known as selective absorbers

20. Selective Absorbers Absorb certain wavelengths of radiation
Also selectively emit radiation
Kirchoff’s Law - good absorbers are good emitters at a particular wavelength, but poor absorbers are poor emitters at the same wavelength
Example:
Glass absorbs UV and IR radiation but not visible

21. Selective Absorbers
Solar radiation passes rather freely through earth's atmosphere, but earth's re-emitted longwave energy either fits through a narrow window or is absorbed by greenhouse gases and re-radiated toward earth
Wavelengths between 8 and 11 μm known as atmospheric window
Clouds can close the window

22. Greenhouse Effect
- Earth's energy balance requires that absorbed solar radiation is emitted to maintain a constant temperature.
- Without natural levels of greenhouse gases absorbing and emitting, this surface temperature would be 33°C cooler than the observed temperature.

23. Enhancements to the Greenhouse Effect
GHG’s contribute to enhancing the Greenhouse effect
Increasing concentrations of Methane, Nitrous Oxide and CFC’s have been shown to have a nearly equal effect when combined as to that of carbon dioxide
Climate models predict the continued warming of the planet will lead to more atmospheric water vapor which will continue to enhance the effect
However ….. The largest and least understood feedbacks in the climate system are the clouds and oceans
Clouds can change area, depth and radiation processes simultaneously with climate change
Ocean temperatures, circulations and sea ice will also have an effect

24. Warming Earth's Atmosphere
- Solar radiation passes first through the upper atmosphere, but only after absorption by earth's surface does it generate sensible heat to warm the ground and generate longwave energy.
- This heat and energy at the surface then warms the atmosphere from below.

25. Incoming Solar Radiation
Solar energy received at the top of the atmosphere is constant at 2 calories per square cm each minute. What is the number typically written as and what is it called?
Albedo is the percent of radiation returning from a surface compared to the amount striking it
Sunlight can be scattered or reflected by particles in the atmosphere
What is another term for scattering?
Why is the sky blue?
Air molecules are smaller than the wavelengths of visible light and are more
Effective scatterers of shorter (blue) wavelengths than longer (red) wavelengths

26. Incoming Solar Radiation
- Solar radiation is scattered and reflected by the atmosphere, clouds, and earth's surface, creating an average albedo of 30%.
- Atmospheric gases and clouds absorb another 19 units, leaving 51 units of shortwave absorbed by the earth's surface.

27. Earth-Atmosphere Energy Balance
Earth's surface absorbs the 51 units of shortwave and 96 more of longwave energy units from atmospheric gases and clouds.
These 147 units gained by earth are due to shortwave and longwave greenhouse gas absorption and emittance.
Earth's surface loses these 147 units through conduction, evaporation, and radiation.

28. Earth's Magnetic Field
Earth's molten metal core creates a magnetic field that covers earth from the south to north pole.

29. Solar Wind
High energy plasma is blown from the sun in a dangerous solar wind, and the magnetosphere deflects this wind to shield the earth.

30. Ions & Aurora Belts
Solar winds entering the magnetosphere excite atmospheric gas electrons.
When the electron de-excites it emits visible radiation.
The aurora is created by these solar winds and de-exciting ions, and has belts of expected occurrence at both poles.